The need for a high-capacity hard disk drive (HDD) is increasing year by year. A presently prevalent magnetic recording medium has an arrangement in which each layer forming the recording medium is evenly formed on the entire substrate surface. When achieving a recording capacity exceeding 500 Gb/in2, however, adjacent data signals are too close to each other. When recording or reproducing the data signals, therefore, a phenomenon in which nearby data to be neither recorded nor reproduced is read out or written occurs.
Accordingly, patterned media have recently extensively been studied as techniques of further increasing the recording density by avoiding the phenomenon as described above. A patterned medium has the feature that a magnetic film is processed into predetermined patterns in advance, and a recording/reproduction head records or reproduces information in accordance with the patterns. As the forms of the processed patterns, a discrete track medium (DTM) in which only servo information and recording tracks are processed and data is recorded in the circumferential direction by the conventional method and a so-called bit patterned medium (BPM) in which not only servo information but also bit patterns are processed in the circumferential direction have been examined.
Since servo information is preformed on the DTM and BPM as described above, it is possible to shorten the conventionally necessary time for magnetically recording the servo information, and reduce the apparatus cost. Also, no magnetic film exists between tracks or magnetization reversal units (bits), so no noise is generated therefrom. This makes it possible to improve the signal quality (signal/noise ratio: SNR), and manufacture a high-density magnetic recording medium and magnetic recording apparatus.
In the DTM and BPM, however, a magnetic film is processed into fine patterns, so the film may be damaged during the processing. As an example, the oxidation of a magnetic element such as Co may deteriorate the magnetic characteristics of the magnetic film, thereby degrading the recording/reproduction characteristics of the medium.
Accordingly, demands have arisen for a simple process that can be implemented while maintaining the recording/reproduction characteristics.